Husqvarna 562xp air leak driving me mad

[Maxchaos]

I picked up this 562xp broken because of bad bearings and seals,as usual.
New piston,used good cylinder,changed everything with new OE bearings and seals and gaskets.
Used motoseal on cylinder base and crankcase mating surface as usual.
Saw started after 2-3 pulls.
Runs strane,idle a bit high,bit of bogs when blipping the throttle.
Started checking for leaks,seemed around the cylinder base,maybe the transfer covers,pulled everything,new gasket with more thickness because saw is After 2020,oring of the transfer covers was fine bit still changed and used some yamabond to seal better.
Closed everything back.
Same problem.Still around cylinder especially on the back so pulled everything again and new boot with motoseal was installed.
SAME IDENTYCAL PROBLEM.
I noticed when you spray on carb the saw dies so must be the carb maybe.
Cleaned and changed every seal with the repair kit with gasket etc. Yes the autotune one too.
New filters too.
Now it's even worse, very high idle and too lean.
Before I put It in the trash,what else can I do without searching for a new carb?
I was thinking maybe the flywheel seal wasn't installed properly,will try to find one new, but there's something strange going on.
Thanks everyone.

 

[cuinrearview]

I seem to remember seeing something @huskihl wrote about some interference around the exhaust side of the cylinder after dropping it, but that may have been after machine work and not just deleting the gasket. May be worth searching on this site for, or maybe pork digits will chime in.

 

[redneckhillbilly]

maybe a cylinder head bolt is too long.

 

[hacskaroly]

Before I put It in the trash,what else can I do without searching for a new carb?

I worked on a 562xp it it gave me fits. Narrowed it down to the carb, an air leak somewhere. The purge bulb would not fill, would just whistle. I replaced the bulb, the lines, new diaphragm kit, cleaned everything really well and still had an air leak. I even used clear fingernail polish around the seams to eliminate any leaks and still did not work. I hooked up the purge bulb directly to the fuel and return line and it pumped like a champ, but when connected to the carb, it failed. New one of those carbs goes for about $120, customer wasn't willing to go for it.

 

[huskihl]

I don’t think it will matter with just a gasket delete, but you can check the front left where the transfer cap screw is close to the case and also on the front right. I don’t believe you can do a gasket delete to a 562 without some clearance work somewhere. I would measure your cylinder extension and see if there is room in the case for it. Many of them hit on top of the bearing pockets

 

[Maxchaos]

maybe a cylinder head bolt is too long.

Mmm,I'm not using the original ones because I don't know where they are. Need to double check this,but the cylinder I think it's well sealed,with yamabond hardened I almost couldn't pull the jug off!

I didn't drop the cylinder,I've used 3 different gasket, 0,5mm 0.75mm and even 1mm,no change! And always used the yamabond or the permatex gasket maker.

Didn't change the fuel lines,I will try with a temporary hose and by-pass the purge bulb :/

 

[Jusgunn3]

I have two of these with scored tops ends…thinking real hard about these rebuilds

 

[Carbday]

Check the boot, especially these locations where the rubber pipe goes through the plastic part (part 12 in picture).

The neck of the rubber part can develop a crack, so make sure to wiggle it a bit to make sure it's intact.

 

[EFSM]

Spraying cleaner on the carb is not a safe check, as any little bit pulled in around a shaft will kill it at idle. I would suspect that the pop-off pressure is too high. I’ve had various 550/562 that I had to trim the metering lever spring in order to give the carburetor enough fuel pressure at idle. It seems to be a design flaw in the carburetors. I know that most carb manufacturers don’t recommend checking pop-off pressures due to possible damage to the pump diaphragm, but these Husqvarna carbs routinely run over 30 psi.

 

[huskihl]

Spraying cleaner on the carb is not a safe check, as any little bit pulled in around a shaft will kill it at idle. I would suspect that the pop-off pressure is too high. I’ve had various 550/562 that I had to trim the metering lever spring in order to give the carburetor enough fuel pressure at idle. It seems to be a design flaw in the carburetors. I know that most carb manufacturers don’t recommend checking pop-off pressures due to possible damage to the pump diaphragm, but these Husqvarna carbs routinely run over 30 psi.

Both brands do since EPA mandated that the tanks can’t vent out into the atmosphere. Pop off needs to be able to hold back pressure buildup inside the tank

 

[Creaky limb tree care]

Have you checked the carb butterfly shafts for play ?

 

[EFSM]

Both brands do since EPA mandated that the tanks can’t vent out into the atmosphere. Pop off needs to be able to hold back pressure buildup inside the tank

That’s strange. As far as I know, Echo is still designing machines with vents that release at 7 psi.

 

[huskihl]

That’s strange. As far as I know, Echo is still designing machines with vents that release at 7 psi.

I wasn’t aware of that. But I will check one to see

 

[EFSM]

I wasn’t aware of that. But I will check one to see

The new injection molded tanks on the string trimmers have different vents. But that has come in just the last couple of years. I not sure exactly what is different about the vents. Let me know.

 

[Maxchaos]

Have you checked the carb butterfly shafts for play ?

Not really,seems tight but I'm waiting for a used carb to see what happens if I swap It,can only be the carb now

 

[Maintenance Chief]

Not really,seems tight but I'm waiting for a used carb to see what happens if I swap It,can only be the carb now

I talked to a McCulloch dealer in New York years ago about tricky air leaks,(rip Bob).
He told me one was giving him fits so he lit up a fat cigar and blocked the exhaust and blew thick smoke down the carb, I believe he used play-do to seal it . Anyway he found a casting void in the case covered by paint, and fixed the problem.

 

[EFSM]

I talked to a McCulloch dealer in New York years ago about tricky air leaks,(rip Bob).
He told me one was giving him fits so he lit up a fat cigar and blocked the exhaust and blew thick smoke down the carb, I believe he used play-do to seal it . Anyway he found a casting void in the case covered by paint, and fixed the problem.

The original owner of our local Stihl dealer would do that too.